Question: Which of these numbers is composite? ${3,\ 11,\ 37,\ 39,\ 83}$
Answer: A composite number is a number that has more than two factors (including 1 and itself). 3, 11, 37, and 83 each have only two factors. The factors of 39 are 1, 3, 13, and 39. Thus, 39 is the composite number.